Copiers often are equipped with corner nip feeders which can be loaded with stacks of sheetstock of a given size for automatically feeding individual sheets into the copier. A corner nip feeder may employ a cartridge for convenience in changing the paperstock. Sometimes the corner nips are built into the cartridges, or they may be part of the copier as in U.S. Pat. No. 4,265,441 (Jonas). Corner nip feeders, with and without cartridges, are also employed in other machines such as printers. Because corner nip feeders typically are designed to dispense flexible sheetstock such as copying paper, they have not been useful for dispensing relatively stiff sheetstock, i.e., sheetstock having a diagonal Taber stiffness substantially exceeding 2 g-cm. In using machines equipped with typical corner nip feeders, it may be necessary to hand-feed sheetstock of such stiffness, e.g., sheets of transparency films, cardstock, and pressure-sensitive adhesive labelstock on releasable carriers.